1. Field of the Invention
The present invention relates to portable devices that dispense chemicals such as insect repellents and/or fragrances.
2. Description of the Background
Various techniques have been developed to provide humans with protection from insect bites. For insect control inside buildings a primary emphasis is placed on trying to keep insects from entering the building at all (e.g. placing screens over windows). This sometimes is supplemented with chemical treatment of room air and/or the use of traps. See e.g. U.S. Pat. Nos. 6,582,714 and 7,175,815, and also U.S. patent application publications 2005/0079113, 2006/0039835, 2006/0137241 and 2007/0036688.
When an individual is outdoors where the area cannot be effectively screened, and the individual is mostly staying in a particular area (e.g. at a picnic, or on a patio near a building), traps and repellents are the primary focus. For instance, the individual can apply an insect repellent to clothing or directly to their skin. However, some individuals may be averse to applying chemicals onto delicate clothing or directly onto the skin. Such individuals may avoid products which direct that type of application. Further, if an individual removes an outer layer of clothing sprayed with the insect repellent, that individual must reapply or else have a higher risk of insect bites.
Another means for providing protection to humans from insect bites is to infuse a general area with insect repellant by use of candles (e.g. citronella candles) or other dispensing devices which disperse repellents into the air. These dispensing devices may be electrical devices that actively distribute the repellent by use of fans for evaporating an insecticide source, automatic sprays of liquid repellent, heating elements with wicks, and the like. The devices may be mounted to a surface, such as a wall or a table top, or rested thereon. A common electrical dispenser for distributing insect repellent includes an insecticide source housed within the dispenser that further provides a fan to blow air past the insecticide source and dispense the material into the air. The insecticide source is often a substrate impregnated with insect repellent or other air treatment chemicals and can accommodate a flow of air through the substrate when used in conjunction with a fan.
However, present electrical devices have drawbacks of limited coverage area. For instance, devices that cannot distribute the active far enough have dramatically reduced protective capabilities to individuals located outside the periphery of the coverage area. In some cases, coverage area is limited due to constraints on electrical power availability, fan size, and motor power requirements that are necessarily in place for meeting certain design factors, such as those required for achieving lightweight, portable dispensers. Attempts to increase the repellent coverage area include increasing the fan speed and/or providing more power to the motor. However, such modifications often lead to increased fan noise that may be a nuisance in the environment and higher power consumption which may be costly and demand more frequent battery replacements. Other attempts include increasing the size of the electrical dispensers and/or utilizing multiple dispensers. However, such solutions may result in bulky and burdensome devices that are not easily portable.
Hence, a need exists for improved devices for dispensing insect control actives and other air treatment chemicals, particularly those that can provide an increased coverage area while maintaining portability and ease of use.